Variety Salutes Young Hollywood: The Jonas Brothers, Kat Graham, Jordin Sparks, Sarah Hyland, Vanessa Hudgens, Diego Boneta   Clearly the world’s future is in good hands, if the dedication to charitable causes that was evident at the Sept. 15 “Variety Power of Youth” is any indication.  On that day, some of Hollywood’s hottest young celebrities filled the backlot at Paramount Studios in Hollywood, despite the record-setting heat in downtown Los Angeles, where temperature reached 103 degrees by mid-afternoon. (Check the photo gallery below for 30+ pictures from this extraordinary event.) The estimated 750 guests came to pay...